1. Field of the Invention
This invention relates to a method of preparing a powdery, pasty or greasy silicone composition, and more particularly to a silicone composition useful as a thickening agent or the like.
2. Description of the Prior Art
Silicone oils, because of their safety and so forth, have been hitherto used as base oils for various compositions in a variety of fields including medical care and cosmetics. They, however, have been relatively highly viscous, usually having a viscosity of 100 cSt or more at 25.degree. C.
In recent years, however, particularly in the fields of medical care and cosmetics, silicone oils with a low viscosity of 100 cSt or less have attracted notices because of their excellent spreadability, light feeling, high safety, etc., and comprehensive studies are made on their use. However, when, for example, a pasty or greasy silicone composition is prepared using the low-viscosity silicone oil as a base oil, a smooth and uniform composition can be obtained with difficulty because a thickening agent must be added in an increased amount, and there also has been involved the problem that the low-viscosity silicone oil is liable to be separated and discharged from the resulting composition. That is, the composition has low stability.
Accordingly, as thickening agents for the low-viscosity silicone oils, it has been hitherto proposed to use organic materials including fatty acid esters of dextrin (Japanese Unexamined Patent Publication (KOKAI) No. 121764/1987, No. 143971/1987, No. 143970/1987, and No. 159489/1988), fatty acid esters of sucrose (Japanese Unexamined Patent publication (KOKAI) No. 235366/1988), trimethylsilyl-substituted polyvinyl alcohols or trimethylsilyl-substituted polysaccharide (Japanese Unexamined Patent Publication (KOKAI) No. 240335/1987), and cellulose ethers containing a fatty acid ester group (Japanese Unexamined Patent Publication (KOKAI) No. 260956/1988).
It has been also proposed to use inorganic materials including organic material-modified clay minerals as the thickening agents (Japanese Unexamined Patent Publication (KOKAI) No. 45656/1987, No. 54759/1987 and No. 72779/1988).
However, use of the above organic materials as thickening agents brings about the problem that the properties such as light feeling and high spreadability may become inferior, which are inherent in the low-viscosity silicone oils. The above inorganic materials also have the disadvantage that they must be used in the presence of water and hence make poor the stability of the resulting composition.